Liquor pump for absorption refrigerating machines



Jan. 29, 1-935. G. MAIURI 1,989,520

LIQUOR PUMP FOR ABSORPTION REFRIGERATING MACHINES Filed April 1'7, 1934 INVf/YTOR Gui Do MHI U R I HTTORNEY Patented Jan. 29, 1935 UNITED STATES PATENT OFFICE LIQUOR PUMP FOR ABSORPTION REFRIG- ERATING MACHINES Application April 17, 1934, Serial No. 720,975

Belgium July s, 1933 4 Claims.

This invention relates to liquor pumps for absorption refrigerating machines, and its object is to provide and arrange a pump in such machines effectively to pump liquor.

A continuous absorption refrigerating machine must usually be provided with a pump which sucks rich ammonia liquor from an absorber at a low pressure and. delivers it into a boiler at a higher pressure.

Rich liquor saturated with ammonia in the absorber, comes to the pump in the condition of a liquid very near to its ebullition point. Consequently, unless precautions are taken, liquor contained in the clearance space of the pumping chamber disengages, during the suction stroke, gaseous ammonia at a pressure equal or superior to the suction pressure, with the result that the suction valve cannot open and the pump sucks nothing.

The above action is very embarassing when the machine is to produce very low temperatures. For example, if the temperature to be obtained at the evaporator is C., the absorber must work at 0.2 atmospheres absolute, and if the temperature is C., at 0.1 atmospheres (that is a vacuum of Under these conditions, suction becomes very difficult, if not impossible, with ordinary pumps. Another case where the pump is required to suck boiling liquor is in resorption refrigerating machines.

The pump which forms the subject of the present invention, eliminates, without constructive complications, the above mentioned disadvantages and ensures regular working under any conditions. This is efiected according to the invention by arranging the pumping chamber of the pump to fill with liquor by gravity and allowing the gases mixed with the liquor to escape freely from the pumping chamber during the suction stroke of the pump. For this purpose, the pump cylinder is horizontally arranged and has upper and lower ports in communication with the suction, through the lower of which the liquor enters by gravity whilst the dissociated gas escapes through the upper thereof. During the compression stroke, no gas is present in the cylinder which is filled with liquor which becomes com-' pressed and delivered past the delivery valve.

Representative examples of pumps arranged in accordance with the invention are illustrated on the accompanying drawingfin which:

Fig. 1 is a diagrammatic longitudinal section of a single acting pump, and

Fig. 2 is a similar view of a duplex pump, ap-

plied to a two-stage absorption refrigerating machine.

In Fig. 1, 0!. denotes the pumping chamber or cylinder of the pump, constituted by a liner I) mounted in a cylinder block 0. This latter is formed with an annular chamber (2, surrounding the cylinder liner b and connected at its lowenportion to a suction pipe e, which is in communication with the rich liquor sump of the absorber of a refrigerating machine, located higher than the pump. At its upper portion, the annular chamber d is connected to a pipe 1 likewise in communication with the absorber, but with the upper part thereof filled with ammonia gas. The chamber d communicates with the cylinder a by means of a number of ports 9 extending through the liner b. When the pump plunger h efiects its stroke from left to right, it first creates a vacuum in the cyl-- inder a, and then it uncovers the ports g, which remain open during the rest of the stroke and during the first portion of the return stroke from right to left. During the time where the ports g are open, the liquid enters, by gravity by the pipe e and drives the gas through the pipe I into the upper portion of the absorber. It is obvious that the level of the liquor in the absorber must be higher than the pump, so that the latter can fill with liquor by gravity. It is seen that even in the case where the liquor is actually boiling, the cylinder must always fill with liquor, which, during the compression stroke, is sent on to the boiler of the refrigerating machine, past a non-return delivery valve i and through a pipe 1'.

The ports g are located at an intermediate situation between the ends of the stroke of the pump plunger 71., so that they remain uncovered and permit the expulsion of gas 'during a portion of the compression stroke, for instance during onequarter to one-half of the revolution of the driving crank.

Should a very extreme vacuum reign in the absorber, it could happen that air is sucked in past the stufling box k of the pump plunger. In order to avoid this, an annular chamber 1 embracing the pump plunger h, is in communication, by a pipe m, with the delivery pipe 9, in such manner that the stuffing box k acts against an internal pressure instead of against a vacuum, thus precluding air being drawn into the cylinder a past the stufling box 10.

It is obvious that the pipes e and I may be substituted by a single pipe, located in the place of I, provided that such single pipe has a diameter sufficient to allow bubbles of gas to ascend therein without interfering with the descent of liquor therein. Likewise, the chamber d, instead of being annular, may be limited to one side only of the pump cylinder a, since all that is necessary is that there should be an outlet at the top and an inlet at the bottom, so that when these are uncovered during the suction stroke, liquor can enter at the bottom and drive out gas bubbles at the top.

It is seen that under the most difficult conditions of working, that is to say when during the suction stroke liquor in the clearance space prevents the formation of any vacuum, gas disengaged by the ebullition of such liquor becomes evacuated during the period of opening of the ports a and is replaced by liquor under the action of gravity, so that the pump always works normally.

Fig. 2 shows diagrammatically a two-stage absorption refrigerating machine which works with a duplex pump arranged to be supplied with liquor by gravity and to evacuate gas, in accordance with the invention. The boiler l of the refrigerating machine, drives off from the rich liquor therein, ammonia vapour at high "presure into the condenser 3, where it is liquefied, (for clarity of the drawing the cooling system by the circulation of water is not illustrated). The liquefied ammonia passes from the condenser 3 into the evaporator coil 6 in which it evaporates, producing cold, and the ammonia vapour thereby produced is sucked away and absorbed by weak liquor in a low pressure absorber 5. This latter receives weak liquor coming from a medium pressure boiler 2. This liquor becomes enriched in the low pressure absorber and is pumped therefrom back to the medium pressure boiler 2. As the pump is located at a lower level than that of the absorber 5, the liquor flows from the latter by the pipe I into the annular chamber d of the pump. The liquor fills the chamber (1 and the-pumping chamber a, and gas bubbles escape up the pipe I and return to the low pressure absorber 5. The pump drives the liquor into the medium pressure boiler 2, through the pipe 1. The ammonia vapour disengaged from the liquor in the medium pressure boiler 2, passes into an absorber 4, at the same pressure, and there is absorbed by the liquor therein. This enriched liquor flows down a pipe I and floods a second annular chamber d and pumping chamber a at the other end of the pump, gas bubbles escaping up the pipe f back to the medium pressure absorber 4. From the pumping chamber a the rich liquor is driven into the high pressure boiler 1, through a pipe 7". This arrangement enables working at very low temperatures, for example 60 to -'l0 C., with a water circulation at high temperature for example +28 to +35 C.

As both ends of the duplex pump are operative the plump plunger is in the form of a piston o with a piston rod 1) of less diameter than the piston. This piston rod p should have a diameter such as to obtain the desired ratio between the capacities of the pumping chambers a and a of the pump. when the vacuum is very extreme,

namely whilst the pumping chamber a is under tween the evaporator and the resorber, and the other pumping chamber such as a the circulation between the absorber and the single boiler.

The pump according to the invention may likewise be employed with refrigerating agents and absorbent liquids, other than ammonia and water which are mentioned by way of example as they are the most frequently employed.

I claim:

1. In a pump for absorption refrigerating machines, a horizontal cylinder having ports in the upper and lower portions thereof, a delivery valve of said cylinder, 9. piston reciprocating in said cylinder and uncovering said ports during its suction stroke and covering said ports during its compression stroke, and a source of absorption liquor elevated above said cylinder and connected to said ports.

2. In a pump for absorption refrigerating machines, a horizontal cylinder having a chamber, a liner in said cylinder covering said chamber and having ports in the upper and lower portions thereof communicating with said chamber, a delivery valve of said cylinder, a piston reciprocating in said cylinder liner and uncovering said ports during its suction stroke and covering said ports during its compression stroke, and a source of absorption liquor elevated above said cylinder and connected to said chamber.

3. In a pump for absorption refrigerating machines, a horizontal cylinder having ports in the upper and lower portions thereof and an annular chamber, a delivery valve of said cylinder, means connecting said annular chamber with the delivery side of said delivery valve, a stufling box closing said cylinder, a piston reciprocating in said cylinder and uncovering said'ports during its suction stroke and covering said ports during its compression stroke,a piston rod of said piston constantly embraced by said annular chamber and extending through said stuffing box, and a source of absorption liquor elevated above said cylinder and connected to said ports.

4. In a pump for two stage absorption refrigerating machines, a horizontal cylinder having two axially separated sets of ports in the upper and lower portions thereof, a delivery valve at each end of said cylinder, a stumng box closing said cylinder, a piston reciprocating in said cylinder and alternately uncovering and covering said sets of ports, a piston rod of said piston extending through said. stufllng box, a source of.

absorption liquor elevated above said cylinder and connected to said set of ports remote from said stufllng box, and a source of absorption liquor at a higher pressure than said first-mentioned source connected to said set of ports nearer said stumng box.

-. GUIDOMAIURI. 

